18 20 22 24 26 28 30 32 34 36 



FORK LENGTH (cm) 



Figure 37. — Percentage length-frequency distributions, by month, 

 of Auxu spp. taken in Japanese waters (Yamashige 1974). 



4.13 Size compwsition 



Although the size of A. rochei in the Japanese com- 

 mercial catch varies widely from 4 to 50 cm, the bulk of 

 the catch usually falls between 20 and 35 cm (Fig. 38) 



NOVEMBER (N-138) 



DECEMBER(N = II2) 



u 



JANUARY (N- 32) 



FEBRUARY (N- 16) 



MARCH (N-^ 89) 



APRIL(N=47) 



-4 \~ 



UA-. 



-j-rT-Tn D-i-j-rt-iFu-.- 



-i- J-rn- 





-Jk 



t 



Jm 



X 



20 25 30 



FORK LENGTH (cm) 



Figure 38. — Length-frequency distribution of Auxis rochei caught 

 near Japan (Hotta 195.S). 



(Hotta 1955; Yokota et al. 1961). Furthermore, the aver- 

 age size of the fish varies considerably from month to 

 month. Hotta (1955), Ishida (1972a), and Morita (1972) 

 observed that the average size was usually smallest in 

 August or September after which it increased gradually 

 until early June of the following year then decreased 

 sharply (Fig. 39). 



In addition to the monthly variation in average size, 

 there is also a large variation in the size range from 

 month to month. Hamada, Morita, Ishida, and 

 Takezawa (1973), who examined lengths of A. rochei 

 caught in waters off Kochi Prefecture in Shikoku (north- 



Figure 39.— Mean and range of fork lengths, by 

 months, of Auxie rochei caught off Kochi 

 Prefecture. Japan (Morita 1972). 



